Is there a post credit scene? Sorry if anyone mentioned it earlier but I'm not reading anyone's comments until I see the movie tomorrow.
There is an app (at least for the iPhone) that will help handle both these problems. It's called Runpee. Fire it up at the beginning of the movie and it will give you a buzz when a good pee-time occurs. It also lists any post-credit sequences.I made the mistake of consuming a far too large soda early in the movie and was in agony by the end - so even if there was a post credits scene, I would have definitely missed it!